Empty Response when POSTing new Entities about frost-server HOT 8 CLOSED

fraunhoferiosb commented on September 25, 2024

Empty Response when POSTing new Entities

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Comments (8)

hylkevds commented on September 25, 2024 1

Thanks. I've added the cors.exposed.headers option to the example filter in web.xml

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hylkevds commented on September 25, 2024

The reason the service does not directly echo the entire entity is that entities can be very large. In one of our projects we have Observations containing several MBs of data. You can imagine that it would be very inefficient if that data is sent twice for every Observation creation.

Req 36 - create-update-delete/deep-insert-status-code

Upon successfully creating an entity, the service response SHALL contain a Location header that contains the URL of the created entity. Upon successful completion the service SHALL respond with 201 Created.

So that's what the service does. You can parse the entity id from the location header, or request the location header and get the entity id from the response to that. Our java client library does the former.

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tobi238 commented on September 25, 2024

Ok, getting the entity id from parsing the location header sounds great.
But actually, I'm not able to get the header when I make a JavaScript POST request in the Browser.
Do you have any idea how to do that?

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hylkevds commented on September 25, 2024

That depends on what framework you use to make the POST request...

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tobi238 commented on September 25, 2024

I've tried XMLHttpRequest, Jquery Ajax und fetch: The Header isn't available no matter which one I use...

XMLHttpRequest:

var json = JSON.stringify({
    "name": "Temperature Monitoring System",
    "description": "Sensor system monitoring area temperature",
    "properties": {
        "Deployment Condition": "Deployed in a third floor balcony",
        "Case Used": "Radiation shield"
    }
});

var request = new XMLHttpRequest();

request.open("POST", "http://localhost:8080/SensorThingsServer-1.0/v1.0/Things");
request.setRequestHeader("Access-Control-Expose-Headers", "location");
request.onreadystatechange = function () {
    console.log(request.getResponseHeader('location'));
    console.log(request.getAllResponseHeaders());
};
request.send(json);

Jquery Ajax:

var json = JSON.stringify({
    "name": "Temperature Monitoring System",
    "description": "Sensor system monitoring area temperature",
    "properties": {
        "Deployment Condition": "Deployed in a third floor balcony",
        "Case Used": "Radiation shield"
    }
});

$.ajax({
    type: "POST",
    url: baseUrl + `/Things`,
    data: json,
    beforeSend: function (request) {
        request.setRequestHeader("Access-Control-Expose-Headers", 'Location');
    },
    success: function (data, status, xhr) {
        console.log(xhr.getResponseHeader('location'));
    },
    complete: (xhr, status) => {
        console.log(xhr.getAllResponseHeaders());
    }
});

fetch:

var json = JSON.stringify({
    "name": "Temperature Monitoring System",
    "description": "Sensor system monitoring area temperature",
    "properties": {
        "Deployment Condition": "Deployed in a third floor balcony",
        "Case Used": "Radiation shield"
    }
});

const myHeaders = new Headers({
    'Content-Type': 'application/json',
    'Access-Control-Expose-Headers': 'Location'
});

fetch("http://localhost:8080/SensorThingsServer-1.0/v1.0/Things", {
      method: 'POST',
      headers: myHeaders,
      body: json
   }).then((response) => {
      console.log(response.headers.get('location'));
   }).catch((error) => {
      throw `Thing konnte nicht erstellt werden`;
});

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hylkevds commented on September 25, 2024

This works for me:

<!DOCTYPE html>
<html>
    <head>
        <title>SensorThings POST Test</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
    </head>
    <body>
        <div></div>
        <script type="text/javascript">
            'use strict';

            jQuery(function () {
                var json = JSON.stringify(
                        {
                            "name": "Temperature Monitoring System",
                            "description": "Sensor system monitoring area temperature",
                            "properties": {
                                "Deployment Condition": "Deployed in a third floor balcony",
                                "Case Used": "Radiation shield"
                            }
                        }
                );
                jQuery.ajax({
                    type: "POST",
                    url: "http://localhost:8080/SensorThingsService/v1.0/Things",
                    data: json,
                    success: function (data, status, xhr) {
                        console.log(xhr.getResponseHeader('location'));
                    },
                    complete: (xhr, status) => {
                        console.log(xhr.getAllResponseHeaders());
                    }
                });
            });
        </script>
    </body>
</html>

Output:

http://localhost:8080/SensorThingsService/v1.0/Things(273)
location: http://localhost:8080/SensorThingsService/v1.0/Things(273)
date: Tue, 24 Oct 2017 14:23:00 GMT
content-length: 0

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tobi238 commented on September 25, 2024

When I run your code I get null for the location header and an empty string for all headers:

null

In the Chrome Developer Tools a can see the Response with the location header:

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tobi238 commented on September 25, 2024

Ok, I solved it. The problem came from the CORS settings in the WEB.INF\web.xml:
I needed to add the following to my cors filter:

<init-param>
    <param-name>cors.exposed.headers</param-name>
    <param-value>Location</param-value>
</init-param>

My complete web.xml file for reference:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
    <servlet>
        <servlet-name>default</servlet-name>
        <servlet-class>org.apache.catalina.servlets.DefaultServlet</servlet-class>
        <init-param>
            <param-name>listings</param-name>
            <param-value>false</param-value>
        </init-param>
		<init-param>
          <param-name>readonly</param-name>
          <param-value>false</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
	
	
   <filter>
        <filter-name>CorsFilter</filter-name>
        <filter-class>org.apache.catalina.filters.CorsFilter</filter-class>
        <init-param>
            <param-name>cors.allowed.origins</param-name>
            <param-value>http://localhost:80, http://localhost:8080, http://localhost:81, http://localhost:8100</param-value>
        </init-param>
        <init-param>
            <param-name>cors.allowed.methods</param-name>
		<param-value>GET,POST,PATCH,HEAD,DELETE,OPTIONS</param-value>
        </init-param>
        <init-param>
            <param-name>cors.support.credentials</param-name>
            <param-value>true</param-value>
        </init-param>
        <init-param>
            <param-name>cors.allowed.headers</param-name>
            <param-value>Origin, Accept, X-Requested-With, Content-Type, Access-Control-Request-Method, Access-Control-Request-Headers, Authorization</param-value>
        </init-param>
	<init-param>
            <param-name>cors.exposed.headers</param-name>
            <param-value>Location</param-value>
        </init-param>
    </filter>

    <filter-mapping>
        <filter-name>CorsFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>

My Function for POSTing new Things and return their ID:

const baseUrl = `http://localhost:8080/SensorThingsServer-1.0/v1.0`
const createThing = () => {
    let thing = {
        "name": "Temperature Monitoring System",
        "description": "Sensor system monitoring area temperature",
        "properties": {
           "Deployment Condition": "Deployed in a third floor balcony",
           "Case Used": "Radiation shield"
        }
    };

    return fetch(`${baseUrl}/Things`, {
        method: 'POST',
        body: JSON.stringify(thing)
    }).then((response) => {
        if (!response.ok) {
            throw response.statusText;
        }
        return parseInt(response.headers.get('location').split('(')
            .filter(function(v){ return v.indexOf(')') > -1})
            .map( function(value) { 
                return value.split(')')[0]
            }).pop());

    }).catch((error) => {
        throw `Thing konnte nicht erstellt werden`;
    });
}

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Empty Response when POSTing new Entities about frost-server HOT 8 CLOSED

Comments (8)

Req 36 - create-update-delete/deep-insert-status-code

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